Thursday, May 18, 2017

Tree of the Week: Flowering Magnolia (Magnolia grandiflora)

Our tree of the week is the Magnolia grandiflora located near the Fitness Center. This is an older, healthy tree that predates the establishment of the arboretum, so its history is unwritten. As the borders of the arboretum expanded, the tree became part of the collection. In November 1997, several gallon-sized pots of rattan vine (Berchemia scandens) were planted under the tree. Today the tree and vines appear to be in strong competition, with the vines growing over-top the tree. You can also find a successful patch of dewberry (Rubus trivialis) growing at the base.

The Magnolia grandiflora flower is the state flower of Louisiana.
Flower tucked behind the rich, green foliage.
In the lower right-hand corner of the photo, note the characteristic rusty color of the underside of the leaf.
This week you will find several low hanging branches with flower buds.
Flower bud detail
The rattan vine (Berchemia scandens) snakes around the trunk of this Magnolia grandiflora.
This photo from late winter (March 9, 2017) shows how successful the rattan vine has been in its competition with the magnolia. The dewberry vine (Rubus trivialis) is in flower at the base of the tree.
The tree seems healthy enough despite the overwhelming success of the vine, but this summer the vine will be trimmed.

You can see additional photos of the arboretum's flowering magnolias here.

For more information about this species consult the following:
United States Department of Agriculture
University of Florida IFAS Extension
Louisiana Plant Identification and Interactive Virtual Tours (LSU AgCenter)

Tuesday, May 16, 2017

What's in Bloom?

In the middle of May, the arboretum collection is displaying a variety of creamy white flowers. The oak-leaf hydrangea bushes (Hydrangea quercifolia) and sweetbay magnolias (Magnolia virginiana) have been in flower for several weeks now. You can't miss the hydrangeas, but you'll need to go looking for the sweetbay flowers. The flowering magnolias (Magnolia grandiflora) have been in bloom all over town, but the trees in the arboretum collection have just now started blooming. On the slopes of the arboretum the viburnums are producing clusters of white flowers, and in the wet areas along the drainage the lizard-tail flowers can be seen. The large leadplant bush (Amorpha paniculata) breaks with the color scheme, showing us its purple and orange flowers in a wild display of racemes.

Oak-leaf hydrangea (Hydrangea quercifolia) flower
Evergreen Sweetbay (Magnolia virginiana var. australis)
Flowering Magnolia (Magnolia grandiflora)
Ashe's viburnum (Viburnum ashei) is a large bush covered in white flowers, located near Mickle Hall.
Lizard-tail (Saururus cernuus) flower and leaves
There are several substantial patches of lizard-tail in the arboretum, along the main drainage that runs north to south.
The purple and orange flowers of the Amorpha paniculata bush add a dash of extra color to the arboretum this month. 
Amorpha paniculata racemes and leaves

Wednesday, May 10, 2017

Tree of the Week: Toothache Tree (Zanthoxylum clava-herculis)

The toothache tree (Zanthoxylum clava-herculis) is known for its peculiar bark. Medicinal use of the inner bark is the origin of the common name 'toothache tree': chewing the inner bark numbs the gums, relieving the pain associated with a toothache. The outer bark of this tree has resulted in another common name: Hercules' club. The whole tree is covered in spines, but the trunk of the tree and its older branches have large thorns, giving the trunk and branches a particularly aggressive appearance, recalling the deadly weapon used by the Greek hero Heracles.

There are three individual toothache trees in the arboretum collection, all growing at the southwest corner of Mickle Hall. Two of the three trees were purchased from Woodlanders Nursery out of Aiken, South Carolina. They were planted in 1989. More than a decade later, Ed Leuck added an additional specimen, collected in Shreveport, from along Clyde Fant Parkway. Interestingly, the younger tree has significantly outpaced the two trees from South Carolina. The specimen from Shreveport is over twice the size of the 1989 plantings.

This is the southwest corner of Mickle Hall, the entrance to the basement of the building. The youngest toothache tree is almost two stories tall, reaching the first floor windows. French mulberry (Callicarpa americana) and coral bean (Erythrina herbacea) grow in its shade. The older two toothache trees are nearby (not pictured), and half the size of the younger tree.
Trunk detail: mottled bark with thorn-tipped corky knobs
Bark detail
Branch with thorns in profile; branchlet also showing thorns
Cluster of unripe fruit
Zanthoxylum clava-herculis leaf detail
You can see additional photos of the arboretum's toothache trees here.

For more information about this species consult the following:
United States Department of Agriculture 
Louisiana Plant Identification and Interactive Virtual Tours (LSU AgCenter) 
Texas A&M Forest Service

Friday, May 5, 2017

Tree of the Week: Sweet Bay Magnolia (Magnolia virginiana)

Sweet bay magnolias (Magnolia virginiana) have been blooming for several weeks in the arboretum. Unfortunately, these flowers are easy to miss because they are not at eye level. There are seven individual sweet bays in the arboretum collection, and most of these trees are well over twenty years old. They are grown up, with the majority of their lower limbs removed. This means that, for the most part, all of the blooms are high up and out of view. Fortunately, the sweet bay magnolias are just as fragrant as the traditional magnolia flower (Magnolia grandiflora), so even if we cannot see the flowers, we still have a good chance of experiencing the divine fragrance that these flowers produce.

The flowers are a creamy white and very fragrant. They are a smaller version of the traditional magnolia flower (Magnolia grandiflora). 
Most flowers are easy to miss because they occur out of sight, but the fragrance of a blooming magnolia will tell you its time to look for flowers.
Underside of leaves
Leaves and flower bud
Bark detail of younger specimen
Mature bark on Magnolia virginiana var. australis

You can see additional photos of the arboretum's sweet bay magnolias here.

For more information about this species consult the following:
United States Department of Agriculture
Louisiana Plant Identification and Interactive Virtual Tours (LSU AgCenter)
University of Florida IFAS Extension

Saturday, April 29, 2017

Tree of the Week: Parsley Hawthorn (Crataegus marshallii) VOLUME II

Not long ago we reviewed the yearly progress of an idiosyncratic native tree. The parsley hawthorn has interesting leaves, beautiful bark, and a noteworthy (bad) smell! Crataegus marshallii is especially important to the arboretum because it is found in healthy, stable populations in Caddo Parish's wild places. This week we're taking a second look at the arboretum's specimens and focusing on the bark.

Most of the year this tree has a beautiful, handsome, mottled bark. During high Spring, a change comes over specimens of this species that are still actively growing. Old bark is sloughed off, and fresh bark is revealed. Both the inside of the old bark and the outside of the new bark are a rich, velvety orange. Catch it while you can! As the new bark ages, it loses the orange color and takes on the familiar mottling of grey, brown, and green. Enjoy the photos below!

Thursday, April 20, 2017

Tree of the Week: American Holly (Ilex opaca)

To most visitors of the arboretum the flowers of the American holly (Ilex opaca) will be passed by unnoticed. The clusters of tiny off-white flowers do not beg attention, and upon further inspection, the flowers produce only the faintest aroma. However, as the video below testifies, the six-legged, airborne visitors of the arboretum appreciate the American holly flowers quite a bit.

American hollies have grown happily in the arboretum. There are five individual trees and all thriving. The largest of the five is the on-site native, located near the Student Union Building. Ed Leuck made sure to give this tree plenty of room to take on its natural pyramidal shape. Only two plantings were made: the botany class of '87 contributed an individual from Bienville Parish, and in 1993, Ed Leuck planted a specimen collected from Cypress Lake. The last two American hollies volunteered at just the right time and in just the right places. They were added to the collection in 2002 and 2003, located not far from the '87 and '93 plantings.
Typical pointy holly leaves are pretty at Christmas but not appreciated while pruning (ouch!)
Flower cluster with leaves
Pollinator hard at work
Trunk detail of 2002 volunteer
Mottled bark of the on-site native

You can see additional photos of the arboretum's American hollies here

For more information about this species consult the following:
United States Department of Agriculture
University of Kentucky
Louisiana Plant Identification and Interactive Virtual Tours (LSU AgCenter)

What's in Bloom?

Spring, she is in full force. The red buckeyes (Aesculus pavia) have been blooming for over a month. Magnolias are just getting started.
The arboretum's fetter-bush (Agarista populifolia) is secluded; you will find it in an out-of-the-way location.
The red buckeyes (Aesculus pavia) continue to shine.
The oak-leaf hydrangea bush (Hydrangea quercifolia) is producing many large white flowers.
Japanese honeysuckle (Lonicera japonica) smells divine. This non-native plant volunteered its way into the arboretum. It remains confined to a French mulberry tree at this time.
The sweet bay magnolia (Magnolia virginiana) is very fragrant.
Sweet bay magnolia interior
 The delicate pink color of the Carolina rose (Rosa carolina) has unfortunately been washed out in this photo. Stop to smell the roses and see it for yourself. You won't be disappointed.
The flowers of the eastern prickly-pear (Opuntia humifusa), while impressive, do not last long. Try to catch them at their best.